Method and Device for Determining Elapsed Sensor Life

ABSTRACT

Methods and systems for determining elapsed sensor life in medical systems, and more specifically continuous analyte monitoring systems.

RELATED APPLICATIONS

The present application is a continuation of U.S. patent application Ser. No. 15/435,214 filed Feb. 16, 2017, which is a continuation of U.S. patent application Ser. No. 14/195,449 filed Mar. 3, 2014, now U.S. Pat. No. 9,574,914, which is a continuation of U.S. patent application Ser. No. 12/495,219 filed Jun. 30, 2009, now U.S. Pat. No. 8,665,091, which is a continuation-in-part application of U.S. patent application Ser. No. 12/117,681, filed May 8, 2008, now U.S. Pat. No. 8,461,985, entitled “Analyte Monitoring System and Methods,” which claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application No. 60/916,744 filed May 8, 2007, entitled “Analyte Monitoring System and Methods”, the disclosures of each of which are incorporated herein by reference for all purposes.

BACKGROUND

The potential for severe complications caused by persistent high analyte levels and analyte fluctuations has provided the impetus to develop data monitoring and management systems. In this regard, attempts have been made to detect and monitor certain analyte levels, e.g., glucose, with the use of analyte monitoring systems designed to continuously or semi-continuously monitor analyte data from a subject. The analyte monitoring systems often include a sensor configured to detect analyte levels and generate signals corresponding to the detected analyte signals. In some analyte monitoring systems, the sensor is inserted in the body of the subject. Typically, such sensors have a sensor life of about a week. Thus, the sensor must be replaced periodically for continuous analyte detection and monitoring.

Occasionally, data monitoring systems undergo a fault condition, such as for example a power loss, power shut-down, Watchdog reset, or various other system or component failures. During these fault conditions, the system often loses data and time so there is no way for the system to recognize the amount of time elapsed during the fault condition. Thus, after fault conditions, it was necessary for the user to replace the sensor even if the fault condition occurred on day 2 of a 5-day or a 7-day sensor. In addition to the financial costs of replacing a sensor that had remaining life expectancy, the new sensor must be calibrated, requiring multiple finger sticks of the user and time. In view of the foregoing, it would be desirable to have a method and apparatus for determining the elapsed sensor life and/or remaining sensor life subsequent to a fault condition in a medical communication system, so that the same sensor can be used after the fault condition.

SUMMARY

The purpose and advantages of the present invention will be set forth in and apparent from the description that follows, as well as will be learned by practice of the invention. Additional advantages of the invention will be realized and attained by the methods and systems particularly pointed out in the written description and claims hereof, as well as from the appended drawings.

To achieve these and other advantages and in accordance with the purpose of the invention, as embodied herein and broadly described, the invention includes devices and methods for analyte monitoring, for example but not limited to, glucose monitoring. In accordance with one aspect of the invention, a method is provided for operating an analyte monitoring system. The method includes providing a signal associated with initiation of an analyte sensor and providing a count from an incrementing counter. The method further includes storing a count that is temporally associated with the signal associated with initiation of the analyte sensor. In one embodiment, initiation of the sensor and signal occurs after placement of the sensor, e.g., transcutaneous implantation or insertion of the sensor to a user. In this regard, the first count commensurate with sensor initiation is saved, for example, in a memory unit, such as a non-volatile memory. After the first count is stored, the counter continues to incrementally count. The incremental count can be based on a periodic cycle associated with calculation of an analyte measurement by the analyte sensor. The periodic cycle can be based on a time interval, e.g., every 30 or 60 seconds, and/or provided in data packets. The periodic calculations of analyte can be transmitted via the data packets to a receiver or transceiver, as rolling data every period.

In accordance with the invention, the method provides a way to determine elapsed (or remaining) sensor life for a particular sensor, for example, by a comparison between the stored first count and the incremental count based on periodic cycles. Further, the elapsed time can be used to restart a sensor life timer and/or calibration timer, if desired.

In a further aspect of the invention, a second signal can be provided, wherein the second signal temporally associated with a second initiation of an analyte is stored, if a fault conditions occurs. In this regard, the elapsed time of the sensor can be determined by a comparison of the stored counts for the first and second signals that are temporally associated with initiation of the sensor and re-initiation of the sensor after the occurrence of a fault condition. For example, but not limitation, a system failure includes a battery drain, power shut-down (voluntary or involuntary), system reset.

In another aspect of the invention, the method includes providing a second counter that incrementally counts each time a new sensor is initialized. Thus, the method includes a first counter that incrementally counts and a second counter that only incrementally counts when a sensor is initialized. In this regard, the second counter can provide information regarding how many sensors have been employed (or initialized) in the data monitoring system.

In one embodiment, the second counter can be used in conjunction with the first counter to determine the elapsed time for a particular sensor. In this regard, the incremental count of the first counter, such as a Hobbs counter provides an indication of time duration, while the second counter, such as a sensor counter, can provide information regarding the occurrence of sensor initiation. In this regard, the count of the Hobbs counter is saved when the sensor counter indicates initiation of a sensor. Thus, the two counters, i.e., a comparison of information derived from both the first counter and the second counter, can be used to determine the elapsed time of an employed sensor.

In another aspect of the invention, a data processing device configured to determine elapsed life of a sensor is provided. The data processing device includes a data processing section coupled to a data communication unit and at least one counter, e.g., Hobbs counter. In accordance with one aspect of the invention, the elapsed life of a sensor is determined by comparing the stored count with the incremented count. In another embodiment, the data processing device includes two counters, e.g., a Hobbs counter and a sensor counter. Elapsed life can be determined by comparing the counts of both counters in conjunction with each other.

The data processing device can further include a storage unit such as a non-volatile memory unit to store the count. The non-volatile memory unit can be disposed in a transmitter or a receiver unit. Further, the data processing device can include an output unit for outputting a message, such as date and time of sensor expiration, data and time for next calibration, or a value derived from the count information, such as remaining life of the sensor. A method further includes displaying a value derived or otherwise associated with the stored count, and/or the incremented count on a display unit. Further, the output unit can be configured to display an alarm when a calibration is needed, and/or when the sensor is close to expiration. The output unit includes one or more of a visual, audible or tactile output. In accordance with one embodiment, the display unit can be a receiver or, if desired, a transmitter. In one embodiment, the display is an OLED color display.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and are intended to provide further explanation of the invention claimed. The accompanying drawings are included to illustrate and provide a further understanding of the method and device of the invention. Together with the description, the drawings serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a block diagram of a data monitoring and management system for practicing one or more embodiments of the present invention;

FIG. 2 is a block diagram of the transmitter unit of the data monitoring and management system shown in FIG. 1 in accordance with one embodiment of the present invention;

FIG. 3 is a block diagram of the receiver/monitor unit of the data monitoring and management system shown in FIG. 1 in accordance with one embodiment of the present invention;

FIG. 4 is a flowchart illustrating data packet procedure including rolling data for transmission in accordance with one embodiment of the present invention;

FIG. 5 is a flowchart illustrating data processing of the received data packet including the rolling data in accordance with one embodiment of the present invention;

FIG. 6 is a block diagram illustrating the sensor and the transmitter unit of the data monitoring and management system of FIG. 1 in accordance with one embodiment of the present invention;

FIG. 7 is a flowchart illustrating data communication using close proximity commands in the data monitoring and management system of FIG. 1 in accordance with one embodiment of the present invention;

FIG. 8 is a flowchart illustrating sensor insertion detection routine in the data monitoring and management system of FIG. 1 in accordance with one embodiment of the present invention;

FIG. 9 is a flowchart illustrating sensor removal detection routine in the data monitoring and management system of FIG. 1 in accordance with one embodiment of the present invention;

FIG. 10 is a flowchart illustrating the pairing or synchronization routine in the data monitoring and management system of FIG. 1 in accordance with one embodiment of the present invention;

FIG. 11 is a flowchart illustrating the pairing or synchronization routine in the data monitoring and management system of FIG. 1 in accordance with another embodiment of the present invention;

FIG. 12 is a flowchart illustrating the power supply determination in the data monitoring and management system of FIG. 1 in accordance with one embodiment of the present invention;

FIG. 13 is a flowchart illustrating close proximity command for RF communication control in the data monitoring and management system of FIG. 1 in accordance with one embodiment of the present invention;

FIG. 14 is a flowchart illustrating analyte sensor identification routine in accordance with one embodiment of the present invention;

FIG. 15 is a flowchart illustrating the analyte sensor life determination in accordance with one embodiment of the present invention; and

FIG. 16 is a flowchart illustrating the analyte sensor life determination in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION

As summarized above and as described in further detail below, in accordance with various embodiments of the invention, there are provided a method and system for operating an analyte monitoring device.

FIG. 1 illustrates a data monitoring and management system such as, for example, analyte (e.g., glucose) monitoring system 100 in accordance with one embodiment of the present invention. The subject invention is further described primarily with respect to a glucose monitoring system for convenience and such description is in no way intended to limit the scope of the invention. It is to be understood that the analyte monitoring system may be configured to monitor a variety of analytes, e.g., lactate, and the like. Analytes that may be monitored include, for example, acetyl choline, amylase, bilirubin, cholesterol, chorionic gonadotropin, creatine kinase (e.g., CK-MB), creatine, DNA, fructosamine, glucose, glutamine, growth hormones, hormones, ketones, lactate, peroxide, prostate-specific antigen, prothrombin, RNA, thyroid stimulating hormone, and troponin. The concentration of drugs, such as, for example, antibiotics (e.g., gentamicin, vancomycin, and the like), digitoxin, digoxin, drugs of abuse, theophylline, and warfarin, may also be monitored. More than one analyte may be monitored by a single system, e.g. a single analyte sensor.

The analyte monitoring system 100 includes a sensor 101, a transmitter unit 102 coupleable to the sensor 101, and a primary receiver unit 104 which is configured to communicate with the transmitter unit 102 via a bi-directional communication link 103. The primary receiver unit 104 may be further configured to transmit data to a data processing terminal 105 for evaluating the data received by the primary receiver unit 104. Moreover, the data processing terminal 105 in one embodiment may be configured to receive data directly from the transmitter unit 102 via a communication link which may optionally be configured for bi-directional communication. Accordingly, transmitter unit 102 and/or receiver unit 104 may include a transceiver.

Also shown in FIG. 1 is an optional secondary receiver unit 106 which is operatively coupled to the communication link and configured to receive data transmitted from the transmitter unit 102. Moreover, as shown in the Figure, the secondary receiver unit 106 is configured to communicate with the primary receiver unit 104 as well as the data processing terminal 105. Indeed, the secondary receiver unit 106 may be configured for bidirectional wireless communication with each or one of the primary receiver unit 104 and the data processing terminal 105. As discussed in further detail below, in one embodiment of the present invention, the secondary receiver unit 106 may be configured to include a limited number of functions and features as compared with the primary receiver unit 104. As such, the secondary receiver unit 106 may be configured substantially in a smaller compact housing or embodied in a device such as a wrist watch, pager, mobile phone, PDA, for example. Alternatively, the secondary receiver unit 106 may be configured with the same or substantially similar functionality as the primary receiver unit 104. The receiver unit may be configured to be used in conjunction with a docking cradle unit, for example for one or more of the following or other functions: placement by bedside, for re-charging, for data management, for night time monitoring, and/or bidirectional communication device.

In one aspect, sensor 101 may include two or more sensors, each configured to communicate with transmitter unit 102. Furthermore, while only one transmitter unit 102, communication link 103, and data processing terminal 105 are shown in the embodiment of the analyte monitoring system 100 illustrated in FIG. 1, it will be appreciated by one of ordinary skill in the art that the analyte monitoring system 100 may include one or more sensors, multiple transmitter units 102, communication links 103, and data processing terminals 105. Moreover, within the scope of the present invention, the analyte monitoring system 100 may be a continuous monitoring system, or semi-continuous, or a discrete monitoring system. In a multi-component environment, each device is configured to be uniquely identified by each of the other devices in the system so that communication conflict is readily resolved between the various components within the analyte monitoring system 100.

In one embodiment of the present invention, the sensor 101 is physically positioned in or on the body of a user whose analyte level is being monitored. The sensor 101 may be configured to continuously sample the analyte level of the user and convert the sampled analyte level into a corresponding data signal for transmission by the transmitter unit 102. In certain embodiments, the transmitter unit 102 may be physically coupled to the sensor 101 so that both devices are integrated in a single housing and positioned on the user's body. The transmitter unit 102 may perform data processing such as filtering and encoding on data signals and/or other functions, each of which corresponds to a sampled analyte level of the user, and in any event transmitter unit 102 transmits analyte information to the primary receiver unit 104 via the communication link 103.

In one embodiment, the analyte monitoring system 100 is configured as a one-way RF communication path from the transmitter unit 102 to the primary receiver unit 104. In such embodiment, the transmitter unit 102 transmits the sampled data signals received from the sensor 101 without acknowledgement from the primary receiver unit 104 that the transmitted sampled data signals have been received. For example, the transmitter unit 102 may be configured to transmit the encoded sampled data signals at a fixed rate (e.g., at one minute intervals) after the completion of the initial power on procedure. Likewise, the primary receiver unit 104 may be configured to detect such transmitted encoded sampled data signals at predetermined time intervals. Alternatively, the analyte monitoring system 100 may be configured with a bi-directional RF (or otherwise) communication between the transmitter unit 102 and the primary receiver unit 104.

Additionally, in one aspect, the primary receiver unit 104 may include two sections. The first section is an analog interface section that is configured to communicate with the transmitter unit 102 via the communication link 103. In one embodiment, the analog interface section may include an RF receiver and an antenna for receiving and amplifying the data signals from the transmitter unit 102, which are thereafter, demodulated with a local oscillator and filtered through a band-pass filter. The second section of the primary receiver unit 104 is a data processing section which is configured to process the data signals received from the transmitter unit 102 such as by performing data decoding, error detection and correction, data clock generation, and data bit recovery.

In operation, upon completing the power-on procedure, the primary receiver unit 104 is configured to detect the presence of the transmitter unit 102 within its range based on, for example, the strength of the detected data signals received from the transmitter unit 102 and/or predetermined transmitter identification information. Upon successful synchronization with the corresponding transmitter unit 102, the primary receiver unit 104 is configured to begin receiving from the transmitter unit 102 data signals corresponding to the user's detected analyte level. More specifically, the primary receiver unit 104 in one embodiment is configured to perform synchronized time hopping with the corresponding synchronized transmitter unit 102 via the communication link 103 to obtain the user's detected analyte level.

Referring again to FIG. 1, the data processing terminal 105 may include a personal computer, a portable computer such as a laptop or a handheld device (e.g., personal digital assistants (PDAs)), and the like, each of which may be configured for data communication with the receiver via a wired or a wireless connection. Additionally, the data processing terminal 105 may further be connected to a data network (not shown) for storing, retrieving and updating data corresponding to the detected analyte level of the user.

Within the scope of the present invention, the data processing terminal 105 may include an infusion device such as an insulin infusion pump (external or implantable) or the like, which may be configured to administer insulin to patients, and which may be configured to communicate with the receiver unit 104 for receiving, among others, the measured analyte level. Alternatively, the receiver unit 104 may be configured to integrate or otherwise couple to an infusion device therein so that the receiver unit 104 is configured to administer insulin therapy to patients, for example, for administering and modifying basal profiles, as well as for determining appropriate boluses for administration based on, among others, the detected analyte levels received from the transmitter unit 102.

Additionally, the transmitter unit 102, the primary receiver unit 104 and the data processing terminal 105 may each be configured for bidirectional wireless communication such that each of the transmitter unit 102, the primary receiver unit 104 and the data processing terminal 105 may be configured to communicate (that is, transmit data to and receive data from) with each other via the wireless communication link 103. More specifically, the data processing terminal 105 may in one embodiment be configured to receive data directly from the transmitter unit 102 via a communication link, where the communication link, as described above, may be configured for bi-directional communication.

In this embodiment, the data processing terminal 105 which may include an insulin pump, may be configured to receive the analyte signals from the transmitter unit 102, and thus, incorporate the functions of the receiver unit 104 including data processing for managing the patient's insulin therapy and analyte monitoring. In one embodiment, the communication link 103 may include one or more of an RF communication protocol, an infrared communication protocol, a Bluetooth® enabled communication protocol, an 802.11x wireless communication protocol, or an equivalent wireless communication protocol which would allow secure, wireless communication of several units (for example, per HIPAA requirements) while avoiding potential data collision and interference.

FIG. 2 is a block diagram of the transmitter of the data monitoring and detection system shown in FIG. 1 in accordance with one embodiment of the present invention. Referring to the Figure, the transmitter unit 102 in one embodiment includes an analog interface 201 configured to communicate with the sensor 101 (FIG. 1), a user input 202, and a temperature detection section 203, each of which is operatively coupled to a transmitter processor 204 such as a central processing unit (CPU). As can be seen from FIG. 2, there are provided four contacts, three of which are electrodes—work electrode (W) 210, guard contact (G) 211, reference electrode (R) 212, and counter electrode (C) 213, each operatively coupled to the analog interface 201 of the transmitter unit 102 for connection to the sensor 101 (FIG. 1). In one embodiment, each of the work electrode (W) 210, guard contact (G) 211, reference electrode (R) 212, and counter electrode (C) 213 may be made using a conductive material that is either printed or etched or ablated, for example, such as carbon which may be printed, or a metal such as a metal foil (e.g., gold) or the like, which may be etched or ablated or otherwise processed to provide one or more electrodes. Fewer or greater electrodes and/or contact may be provided in certain embodiments.

Further shown in FIG. 2 are a transmitter serial communication section 205 and an RF transmitter 206, each of which is also operatively coupled to the transmitter processor 204. Moreover, a power supply 207 such as a battery is also provided in the transmitter unit 102 to provide the necessary power for the transmitter unit 102.

Additionally, as can be seen from the Figure, clock 208 is provided to, among others, supply real time information to the transmitter processor 204.

In one embodiment, a unidirectional input path is established from the sensor 101 (FIG. 1) and/or manufacturing and testing equipment to the analog interface 201 of the transmitter unit 102, while a unidirectional output is established from the output of the RF transmitter 206 of the transmitter unit 102 for transmission to the primary receiver unit 104. In this manner, a data path is shown in FIG. 2 between the aforementioned unidirectional input and output via a dedicated link 209 from the analog interface 201 to serial communication section 205, thereafter to the processor 204, and then to the RF transmitter 206. As such, in one embodiment, via the data path described above, the transmitter unit 102 is configured to transmit to the primary receiver unit 104 (FIG. 1), via the communication link 103 (FIG. 1), processed and encoded data signals received from the sensor 101 (FIG. 1). Additionally, the unidirectional communication data path between the analog interface 201 and the RF transmitter 206 discussed above allows for the configuration of the transmitter unit 102 for operation upon completion of the manufacturing process as well as for direct communication for diagnostic and testing purposes.

As discussed above, the transmitter processor 204 is configured to transmit control signals to the various sections of the transmitter unit 102 during the operation of the transmitter unit 102. In one embodiment, the transmitter processor 204 also includes a memory (not shown) for storing data such as the identification information for the transmitter unit 102, as well as the data signals received from the sensor 101. The stored information may be retrieved and processed for transmission to the primary receiver unit 104 under the control of the transmitter processor 204. Furthermore, the power supply 207 may include a commercially available battery, which may be a rechargeable battery.

In certain embodiments, the transmitter unit 102 is also configured such that the power supply section 207 is capable of providing power to the transmitter for a minimum of about three months of continuous operation, e.g., after having been stored for about eighteen months such as stored in a low-power (non-operating) mode. In one embodiment, this may be achieved by the transmitter processor 204 operating in low power modes in the non-operating state, for example, drawing no more than approximately 1 μA of current. Indeed, in one embodiment, a step during the manufacturing process of the transmitter unit 102 may place the transmitter unit 102 in the lower power, non-operating state (i.e., post-manufacture sleep mode). In this manner, the shelf life of the transmitter unit 102 may be significantly improved. Moreover, as shown in FIG. 2, while the power supply unit 207 is shown as coupled to the processor 204, and as such, the processor 204 is configured to provide control of the power supply unit 207, it should be noted that within the scope of the present invention, the power supply unit 207 is configured to provide the necessary power to each of the components of the transmitter unit 102 shown in FIG. 2.

Referring back to FIG. 2, the power supply section 207 of the transmitter unit 102 in one embodiment may include a rechargeable battery unit that may be recharged by a separate power supply recharging unit (for example, provided in the receiver unit 104) so that the transmitter unit 102 may be powered for a longer period of usage time. Moreover, in one embodiment, the transmitter unit 102 may be configured without a battery in the power supply section 207, in which case the transmitter unit 102 may be configured to receive power from an external power supply source (for example, a battery) as discussed in further detail below.

Referring yet again to FIG. 2, the temperature detection section 203 of the transmitter unit 102 is configured to monitor the temperature of the skin near the sensor insertion site. The temperature reading is used to adjust the analyte readings obtained from the analog interface 201. In certain embodiments, the RF transmitter 206 of the transmitter unit 102 may be configured for operation in the frequency band of approximately 315 MHz to approximately 322 MHz, for example, in the United States. In certain embodiments, the RF transmitter 206 of the transmitter unit 102 may be configured for operation in the frequency band of approximately 400 MHz to approximately 470 MHz. Further, in one embodiment, the RF transmitter 206 is configured to modulate the carrier frequency by performing Frequency Shift Keying and Manchester encoding. In one embodiment, the data transmission rate is about 19,200 symbols per second, with a minimum transmission range for communication with the primary receiver unit 104.

Referring yet again to FIG. 2, also shown is a leak detection circuit 214 coupled to the guard contact (G) 211 and the processor 204 in the transmitter unit 102 of the data monitoring and management system 100. The leak detection circuit 214 in accordance with one embodiment of the present invention may be configured to detect leakage current in the sensor 101 to determine whether the measured sensor data are corrupt or whether the measured data from the sensor 101 is accurate. Exemplary analyte systems that may be employed are described in, for example, U.S. Pat. Nos. 6,134,461, 6,175,752, 6,121,611, 6,560,471, 6,746,582, and elsewhere, the disclosure of each of which are incorporated by reference for all purposes.

FIG. 3 is a block diagram of the receiver/monitor unit of the data monitoring and management system shown in FIG. 1 in accordance with one embodiment of the present invention. Referring to FIG. 3, the primary receiver unit 104 includes an analyte test strip, e.g., blood glucose test strip, interface 301, an RF receiver 302, an input 303, a temperature detection section 304, and a clock 305, each of which is operatively coupled to a receiver processor 307. As can be further seen from the Figure, the primary receiver unit 104 also includes a power supply 306 operatively coupled to a power conversion and monitoring section 308. Further, the power conversion and monitoring section 308 is also coupled to the receiver processor 307. Moreover, also shown are a receiver serial communication section 309, and an output 310, each operatively coupled to the receiver processor 307.

In one embodiment, the test strip interface 301 includes a glucose level testing portion to receive a manual insertion of a glucose test strip, and thereby determine and display the glucose level of the test strip on the output 310 of the primary receiver unit 104. This manual testing of glucose may be used to calibrate the sensor 101 or otherwise. The RF receiver 302 is configured to communicate, via the communication link 103 (FIG. 1) with the RF transmitter 206 of the transmitter unit 102, to receive encoded data signals from the transmitter unit 102 for, among others, signal mixing, demodulation, and other data processing. The input 303 of the primary receiver unit 104 is configured to allow the user to enter information into the primary receiver unit 104 as needed. In one aspect, the input 303 may include one or more keys of a keypad, a touch-sensitive screen, or a voice-activated input command unit. The temperature detection section 304 is configured to provide temperature information of the primary receiver unit 104 to the receiver processor 307, while the clock 305 provides, among others, real time information to the receiver processor 307.

Each of the various components of the primary receiver unit 104 shown in FIG. 3 is powered by the power supply 306 which, in one embodiment, includes a battery. Furthermore, the power conversion and monitoring section 308 is configured to monitor the power usage by the various components in the primary receiver unit 104 for effective power management and to alert the user, for example, in the event of power usage which renders the primary receiver unit 104 in sub-optimal operating conditions. An example of such sub-optimal operating condition may include, for example, operating the vibration output mode (as discussed below) for a period of time thus substantially draining the power supply 306 while the processor 307 (thus, the primary receiver unit 104) is turned on. Moreover, the power conversion and monitoring section 308 may additionally be configured to include a reverse polarity protection circuit such as a field effect transistor (FET) configured as a battery activated switch.

The serial communication section 309 in the primary receiver unit 104 is configured to provide a bi-directional communication path from the testing and/or manufacturing equipment for, among others, initialization, testing, and configuration of the primary receiver unit 104. Serial communication section 309 can also be used to upload data to a computer, such as time-stamped blood glucose data. The communication link with an external device (not shown) can be made, for example, by cable, infrared (IR) or RF link. The output 310 of the primary receiver unit 104 is configured to provide, among others, a graphical user interface (GUI) such as a liquid crystal display (LCD) for displaying information. Additionally, the output 310 may also include an integrated speaker for outputting audible signals as well as to provide vibration output as commonly found in handheld electronic devices, such as mobile telephones presently available. In a further embodiment, the primary receiver unit 104 also includes an electro-luminescent lamp configured to provide backlighting to the output 310 for output visual display in dark ambient surroundings.

Referring back to FIG. 3, the primary receiver unit 104 in one embodiment may also include a storage section such as a programmable, non-volatile memory device as part of the processor 307, or provided separately in the primary receiver unit 104, operatively coupled to the processor 307. The processor 307 may be configured to synchronize with a transmitter, e.g., using Manchester decoding or the like, as well as error detection and correction upon the encoded data signals received from the transmitter unit 102 via the communication link 103.

Additional description of the RF communication between the transmitter unit 102 and the primary receiver unit 104 (or with the secondary receiver unit 106) that may be employed in embodiments of the subject invention is disclosed in U.S. application Ser. No. 11/060,365 filed Feb. 16, 2005, now U.S. Pat. No. 8,771,183, entitled “Method and System for Providing Data Communication in Continuous Glucose Monitoring and Management System” the disclosure of which is incorporated herein by reference for all purposes.

Referring to the Figures, in one embodiment, the transmitter unit 102 (FIG. 1) may be configured to generate data packets for periodic transmission to one or more of the receiver units 104, 106, where each data packet includes in one embodiment two categories of data—urgent data and non-urgent data. For example, urgent data such as for example glucose data from the sensor and/or temperature data associated with the sensor may be packed in each data packet in addition to non-urgent data, where the non-urgent data is rolled or varied with each data packet transmission.

That is, the non-urgent data is transmitted at a timed interval so as to maintain the integrity of the analyte monitoring system without being transmitted over the RF communication link with each data transmission packet from the transmitter unit 102. In this manner, the non-urgent data, for example that are not time sensitive, may be periodically transmitted (and not with each data packet transmission) or broken up into predetermined number of segments and sent or transmitted over multiple packets, while the urgent data is transmitted substantially in its entirety with each data transmission.

Referring again to the Figures, upon receiving the data packets from the transmitter unit 102, the one or more receiver units 104, 106 may be configured to parse the received data packet to separate the urgent data from the non-urgent data, and also, may be configured to store the urgent data and the non-urgent data, e.g., in a hierarchical manner. In accordance with the particular configuration of the data packet or the data transmission protocol, more or less data may be transmitted as part of the urgent data, or the non-urgent rolling data. That is, within the scope of the present disclosure, the specific data packet implementation such as the number of bits per packet, and the like, may vary based on, among others, the communication protocol, data transmission time window, and so on.

In an exemplary embodiment, different types of data packets may be identified accordingly. For example, identification in certain exemplary embodiments may include—(1) single sensor, one minute of data, (2) two or multiple sensors, (3) dual sensor, alternate one minute data, and (4) response packet. For single sensor one minute data packet, in one embodiment, the transmitter unit 102 may be configured to generate the data packet in the manner, or similar to the manner, shown in Table 1 below.

TABLE 1 Single Sensor, One Minute of Data Number of Bits Data Field 8 Transmit Time 14 Sensor 1 Current Data 14 Sensor 1 Historic Data 8 Transmit Status 12 AUX Counter 12 AUX Thermistor 1 12 AUX Thermistor 2 8 Rolling-Data-1

As shown in Table 1 above, the transmitter data packet in one embodiment may include 8 bits of transmit time data, 14 bits of current sensor data, 14 bits of preceding sensor data, 8 bits of transmitter status data, 12 bits of auxiliary counter data, 12 bits of auxiliary thermistor 1 data, 12 bits of auxiliary thermistor 1 data and 8 bits of rolling data. In one embodiment of the present invention, the data packet generated by the transmitter for transmission over the RF communication link may include all or some of the data shown above in Table 1.

Referring back, the 14 bits of the current sensor data provides the real time or current sensor data associated with the detected analyte level, while the 14 bits of the sensor historic or preceding sensor data includes the sensor data associated with the detected analyte level one minute ago. In this manner, in the case where the receiver unit 104, 106 drops or fails to successfully receive the data packet from the transmitter unit 102 in the minute by minute transmission, the receiver unit 104, 106 may be able to capture the sensor data of a prior minute transmission from a subsequent minute transmission.

Referring again to Table 1, the Auxiliary data in one embodiment may include one or more of the patient's skin temperature data, a temperature gradient data, reference data, and counter electrode voltage. The transmitter status field may include status data that is configured to indicate corrupt data for the current transmission (for example, if shown as BAD status (as opposed to GOOD status which indicates that the data in the current transmission is not corrupt)). Furthermore, the rolling data field is configured to include the non-urgent data, and in one embodiment, may be associated with the time-hop sequence number. In addition, the Transmitter Time field in one embodiment includes a protocol value that is configured to start at zero and is incremented by one with each data packet. In one aspect, the transmitter time data may be used to synchronize the data transmission window with the receiver unit 104, 106, and also, provide an index for the Rolling data field.

In a further embodiment, the transmitter data packet may be configured to provide or transmit analyte sensor data from two or more independent analyte sensors. The sensors may relate to the same or different analyte or property. In such a case, the data packet from the transmitter unit 102 may be configured to include 14 bits of the current sensor data from both sensors in the embodiment in which 2 sensors are employed. In this case, the data packet does not include the immediately preceding sensor data in the current data packet transmission. Instead, a second analyte sensor data is transmitted with a first analyte sensor data.

TABLE 2 Dual Sensor Data Number of Bits Data Field 8 Transmit Time 14 Sensor 1 Current Data 14 Sensor 2 Historic Data 8 Transmit Status 12 AUX Counter 12 AUX Thermistor 1 12 AUX Thermistor 2 8 Rolling-Data-1

In a further embodiment, the transmitter data packet may be alternated with each transmission between two analyte sensors, for example, alternating between the data packet shown in Table 3 and Table 4 below.

TABLE 3 Sensor Data Packet Alternate 1 Number of Bits Data Field 8 Transmit Time 14 Sensor 1 Current Data 14 Sensor 1 Historic Data 8 Transmit Status 12 AUX Counter 12 AUX Thermistor 1 12 AUX Thermistor 2 8 Rolling-Data-1

TABLE 4 Sensor Data Packet Alternate 2 Number of Bits Data Field 8 Transmit Time 14 Sensor 1 Current Data 14 Sensor 2 Historic Data 8 Transmit Status 12 AUX Counter 12 AUX Thermistor 1 12 AUX Thermistor 2 8 Rolling-Data-1

As shown above in reference to Tables 3 and 4, the minute by minute data packet transmission from the transmitter unit 102 (FIG. 1) in one embodiment may alternate between the data packet shown in Table 3 and the data packet shown in Table 4. More specifically, the transmitter unit 102 may be configured in one embodiment to transmit the current sensor data of the first sensor and the preceding sensor data of the first sensor (Table 3), as well as the rolling data, and further, at the subsequent transmission, the transmitter unit 102 may be configured to transmit the current sensor data of the first and the second sensor in addition to the rolling data (Table 4).

In one embodiment, the rolling data transmitted with each data packet may include a sequence of various predetermined types of data that are considered not-urgent or not time sensitive. That is, in one embodiment, the following list of data shown in Table 5 may be sequentially included in the 8 bits of transmitter data packet, and not transmitted with each data packet transmission of the transmitter (for example, with each 60 second data transmission from the transmitter unit 102).

TABLE 5 Rolling Data Time Slot Bits Rolling Data 0 8 Mode 1 8 Glucose 1 Slope 2 8 Glucose 2 Slope 3 8 Ref-R 4 8 Hobbs Counter, Ref-R 5 8 Hobbs Counter 6 8 Hobbs Counter 7 8 Sensor Count

As can be seen from Table 5 above, in one embodiment, a sequence of rolling data are appended or added to the transmitter data packet with each data transmission time slot. In one embodiment, there may be 256 time slots for data transmission by the transmitter unit 102 (FIG. 1), and where, each time slot is separated by approximately 60 second interval. For example, referring to the Table 5 above, the data packet in transmission time slot 0 (zero) may include operational mode data (Mode) as the rolling data that is appended to the transmitted data packet. At the subsequent data transmission time slot (for example, approximately 60 seconds after the initial time slot (0)), the transmitted data packet may include the analyte sensor 1 calibration factor information (Glucose 1 slope) as the rolling data. In this manner, with each data transmission, the rolling data may be updated over the 256 time slot cycle.

Referring again to Table 5, each rolling data field is described in further detail for various embodiments. For example, the Mode data may include information related to the different operating modes such as, but not limited to, the data packet type, the type of battery used, diagnostic routines, single sensor or multiple sensor input, or type of data transmission (RF communication link or other data link such as serial connection). Further, the Glucose 1-slope data may include an 8-bit scaling factor or calibration data for first sensor (scaling factor for sensor 1 data), while Glucose 2-slope data may include an 8-bit scaling factor or calibration data for the second analyte sensor (in the embodiment including more than one analyte sensors).

In addition, the Ref-R data may include 12 bits of on-board reference resistor used to calibrate the temperature measurement in the thermistor circuit (where 8 bits are transmitted in time slot 3, and the remaining 4 bits are transmitted in time slot 4), and the 20-bit Hobbs counter data may be separately transmitted in three time slots (for example, in time slot 4, time slot 5 and time slot 6) to add up to 20 bits. In one embodiment, the Hobbs counter may be configured to count each occurrence of the data transmission (for example, a packet transmission at approximately 60 second intervals) and may be incremented by a count of one (1).

In one aspect, the Hobbs counter is stored in a nonvolatile memory of the transmitter unit 102 (FIG. 1) and may be used to ascertain the power supply status information such as, for example, the estimated battery life remaining in the transmitter unit 102. That is, with each sensor replacement, the Hobbs counter is not reset, but rather, continues the count with each replacement of the sensor 101 to establish contact with the transmitter unit 102 such that, over an extended usage time period of the transmitter unit 102, it may be possible to determine, based on the Hobbs count information, the amount of consumed battery life in the transmitter unit 102, and also, an estimated remaining life of the battery in the transmitter unit 102.

That is, in one embodiment, the 20 bit Hobbs counter is incremented by one each time the transmitter unit 102 transmits a data packet (for example, approximately each 60 seconds), and based on the count information in the Hobbs counter, in one aspect, the battery life of the transmitter unit 102 may be estimated. In this manner, in configurations of the transmitter unit 620 (see FIG. 6) where the power supply is not a replaceable component but rather, embedded within the housing the transmitter unit 620, it is possible to estimate the remaining life of the embedded battery within the transmitter unit 620. Moreover, the Hobbs counter is configured to remain persistent in the memory device of the transmitter unit 620 such that, even when the transmitter unit power is turned off or powered down (for example, during the periodic sensor replacement, RF transmission turned off period and the like), the Hobbs counter information is retained.

Referring to Table 5 above, the transmitted rolling data may also include 8 bits of sensor count information (for example, transmitted in time slot 7). The 8 bit sensor counter is incremented by one each time a new sensor is connected to the transmitter unit. The ASIC configuration of the transmitter unit (or a microprocessor based transmitter configuration or with discrete components) may be configured to store in a nonvolatile memory unit the sensor count information and transmit it to the primary receiver unit 104 (for example). In turn, the primary receiver unit 104 (and/or the secondary receiver unit 106) may be configured to determine whether it is receiving data from the transmitter unit that is associated with the same sensor (based on the sensor count information), or from a new or replaced sensor (which will have a sensor count incremented by one from the prior sensor count). In this manner, in one aspect, the receiver unit (primary or secondary) may be configured to prevent reuse of the same sensor by the user based on verifying the sensor count information associated with the data transmission received from the transmitter unit 102. In addition, in a further aspect, user notification may be associated with one or more of these parameters. Further, the receiver unit (primary or secondary) may be configured to detect when a new sensor has been inserted, and thus prevent erroneous application of one or more calibration parameters determined in conjunction with a prior sensor, that may potentially result in false or inaccurate analyte level determination based on the sensor data.

FIG. 4 is a flowchart illustrating a data packet procedure including rolling data for transmission in accordance with one embodiment of the present invention. Referring to FIG. 4, in one embodiment, a counter is initialized (for example, to T=0) (410). Thereafter the associated rolling data is retrieved from memory device, for example (420), and also, the time sensitive or urgent data is retrieved (430). In one embodiment, the retrieval of the rolling data (420) and the retrieval of the time sensitive data (430) may be retrieved at substantially the same time.

Referring back to FIG. 4, with the rolling data and the time sensitive data, for example, the data packet for transmission is generated (440), and upon transmission, the counter is incremented by one (450) and the routine returns to retrieval of the rolling data (420). In this manner, in one embodiment, the urgent time sensitive data as well as the non-urgent data may be incorporated in the same data packet and transmitted by the transmitter unit 102 (FIG. 1) to a remote device such as one or more of the receivers 104, 106. Furthermore, as discussed above, the rolling data may be updated at a predetermined time interval which is longer than the time interval for each data packet transmission from the transmitter unit 102 (FIG. 1).

FIG. 5 is a flowchart illustrating data processing of the received data packet including the rolling data in accordance with one embodiment of the present invention. Referring to FIG. 5, when the data packet is received (510) (for example, by one or more of the receivers 104, 106, in one embodiment), the received data packet is parsed so that the urgent data may be separated from the not-urgent data (stored in, for example, the rolling data field in the data packet) (520). Thereafter the parsed data is suitably stored in an appropriate memory or storage device (530).

In the manner described above, in accordance with one embodiment of the present invention, there is provided method and apparatus for separating non-urgent type data (for example, data associated with calibration) from urgent type data (for example, monitored analyte related data) to be transmitted over the communication link to minimize the potential burden or constraint on the available transmission time. More specifically, in one embodiment, non-urgent data may be separated from data that is required by the communication system to be transmitted immediately, and transmitted over the communication link together while maintaining a minimum transmission time window. In one embodiment, the non-urgent data may be parsed or broken up in to a number of data segments, and transmitted over multiple data packets. The time sensitive immediate data (for example, the analyte sensor data, temperature data, etc.), may be transmitted over the communication link substantially in its entirety with each data packet or transmission.

FIG. 6 is a block diagram illustrating the sensor and the transmitter unit of the data monitoring and management system of FIG. 1 in accordance with one embodiment of the present invention. Referring to FIG. 6, in one aspect, a transmitter unit 620 is provided in a substantially water tight and sealed housing. The transmitter unit 620 includes respective contacts (WRK, REF, CNTR, and GRD) for respectively establishing electrical contact with one or more of the working electrode, the reference electrode, the counter electrode and the ground terminal (or guard trace) of the sensor 610. Also shown in FIG. 6 is a conductivity bar/trace 611 provided on the sensor 610. For example, in one embodiment, the conductivity bar/trace 611 may comprise a carbon trace on a substrate layer of the sensor 610. In this manner, in one embodiment, when the sensor 610 is coupled to the transmitter unit 620, electrical contact is established, for example, via the conductivity bar/trace 611 between the contact pads or points of the transmitter unit 620 (for example, at the counter electrode contact (CNTR) and the ground terminal contact (GRD) such that the transmitter unit 620 may be powered for data communication.

That is, during manufacturing of the transmitter unit 620, in one aspect, the transmitter unit 620 is configured to include a power supply such as battery 621. Further, during the initial non-use period (e.g., post manufacturing sleep mode), the transmitter unit 620 is configured such that it is not used and thus drained by the components of the transmitter unit 620. During the sleep mode, and prior to establishing electrical contact with the sensor 610 via the conductivity bar/trace 611, the transmitter unit 620 is provided with a low power signal from, for example, a low power voltage comparator 622, via an electronic switch 623 to maintain the low power state of, for example, the transmitter unit 620 components. Thereafter, upon connection with the sensor 610, and establishing electrical contact via the conductivity bar/trace 611, the embedded power supply 621 of the transmitter unit 620 is activated or powered up so that some of all of the components of the transmitter unit 620 are configured to receive the necessary power signals for operations related to, for example, data communication, processing and/or storage.

In one aspect, since the transmitter unit 620 is configured to a sealed housing without a separate replaceable battery compartment, in this manner, the power supply of the battery 621 is preserved during the post manufacturing sleep mode prior to use.

In a further aspect, the transmitter unit 620 may be disposed or positioned on a separate on-body mounting unit that may include, for example, an adhesive layer (on its bottom surface) to firmly retain the mounting unit on the skin of the user, and which is configured to receive or firmly position the transmitter unit 620 on the mounting unit during use. In one aspect, the mounting unit may be configured to at least partially retain the position of the sensor 610 in a transcutaneous manner so that at least a portion of the sensor is in fluid contact with the analyte of the user. Example embodiments of the mounting or base unit and its cooperation or coupling with the transmitter unit are provided, for example, in U.S. Pat. No. 6,175,752, incorporated herein by reference for all purposes.

In such a configuration, the power supply for the transmitter unit 620 may be provided within the housing of the mounting unit such that, the transmitter unit 620 may be configured to be powered on or activated upon placement of the transmitter unit 620 on the mounting unit and in electrical contact with the sensor 610. For example, the sensor 610 may be provided pre-configured or integrated with the mounting unit and the insertion device such that, the user may position the sensor 610 on the skin layer of the user using the insertion device coupled to the mounting unit. Thereafter, upon transcutaneous positioning of the sensor 610, the insertion device may be discarded or removed from the mounting unit, leaving behind the transcutaneously positioned sensor 610 and the mounting unit on the skin surface of the user.

Thereafter, when the transmitter unit 620 is positioned on, over or within the mounting unit, the battery or power supply provided within the mounting unit is configured to electrically couple to the transmitter unit 620 and/or the sensor 610.

Given that the sensor 610 and the mounting unit are provided as replaceable components for replacement every 3, 5, 7 days or other predetermined time periods, the user is conveniently not burdened with verifying the status of the power supply providing power to the transmitter unit 620 during use. That is, with the power supply or battery replaced with each replacement of the sensor 610, a new power supply or battery will be provided with the new mounting unit for use with the transmitter unit 620.

Referring to FIG. 6 again, in one aspect, when the sensor 610 is removed from the transmitter unit 620 (or vice versa), the electrical contact is broken and the conductivity bar/trace 611 returns to an open circuit. In this case, the transmitter unit 620 may be configured, to detect such condition and generate a last gasp transmission sent to the primary receiver unit 104 (and/or the secondary receiver unit 106) indicating that the sensor 610 is disconnected from the transmitter unit 620, and that the transmitter unit 620 is entering a powered down (or low power off) state. And the transmitter unit 620 is powered down into the sleep mode since the connection to the power supply (that is embedded within the transmitter unit 620 housing) is broken.

In this manner, in one aspect, the processor 624 of the transmitter unit 620 may be configured to generate the appropriate one or more data or signals associated with the detection of sensor 610 disconnection for transmission to the receiver unit 104 (FIG. 1), and also, to initiate the power down procedure of the transmitter unit 620. In one aspect, the components of the transmitter unit 620 may be configured to include application specific integrated circuit (ASIC) design with one or more state machines and one or more nonvolatile and/or volatile memory units such as, for example, EEPROMs and the like.

Referring again to FIGS. 1 and 6, in one embodiment, the communication between the transmitter unit 620 (or 102 of FIG. 1) and the primary receiver unit 104 (and/or the secondary receiver unit 106) may be based on close proximity communication where bi-directional (or uni-directional) wireless communication is established when the devices are physically located in close proximity to each other. That is, in one embodiment, the transmitter unit 620 may be configured to receive very short range commands from the primary receiver unit 104 (FIG. 1) and perform one or more specific operations based on the received commands from the receiver unit 104.

In one embodiment, to maintain secure communication between the transmitter unit and the data receiver unit, the transmitter unit ASIC may be configured to generate a unique close proximity key at power on or initialization. In one aspect, the 4 or 8 bit key may be generated based on, for example, the transmitter unit identification information, and which may be used to prevent undesirable or unintended communication. In a further aspect, the close proximity key may be generated by the receiver unit based on, for example, the transmitter identification information received by the transmitter unit during the initial synchronization or pairing procedure of the transmitter and the receiver units.

Referring again to FIGS. 1 and 6, in one embodiment, the transmitter unit ASIC configuration may include a 32 KHz oscillator and a counter which may be configured to drive the state machine in the transmitter unit ASIC. The transmitter ASIC configuration may include a plurality of close proximity communication commands including, for example, new sensor initiation, pairing with the receiver unit, and RF communication control, among others. For example, when a new sensor is positioned and coupled to the transmitter unit so that the transmitter unit is powered on, the transmitter unit is configured to detect or receive a command from the receiver unit positioned in close proximity to the transmitter unit. For example, the receiver unit may be positioned within a couple of inches of the on-body position of the transmitter unit, and when the user activates or initiates a command associated with the new sensor initiation from the receiver unit, the transmitter unit is configured to receive the command from the receiver and, in its response data packet, transmit, among others, its identification information back to the receiver unit.

In one embodiment, the initial sensor initiation command does not require the use of the close proximity key. However, other predefined or preconfigured close-proximity commands may be configured to require the use of the 8 bit key (or a key of a different number of bits). For example, in one embodiment, the receiver unit may be configured to transmit a RF on/off command to turn on/off the RF communication module or unit in the transmitter unit 102. Such RF on/off command in one embodiment includes the close proximity key as part of the transmitted command for reception by the transmitter unit.

During the period that the RF communication module or unit is turned off based on the received close proximity command, the transmitter unit does not transmit any data, including any glucose related data. In one embodiment, the glucose related data from the sensor which are not transmitted by the transmitter unit during the time period when the RF communication module or unit of the transmitter unit is turned off may be stored in a memory or storage unit of the transmitter unit for subsequent transmission to the receiver unit when the transmitter unit RF communication module or unit is turned back on based on the RF-on command from the receiver unit. In this manner, in one embodiment, the transmitter unit may be powered down (temporarily, for example, during air travel) without removing the transmitter unit from the on-body position.

FIG. 7 is a flowchart illustrating data communication using close proximity commands in the data monitoring and management system of FIG. 1 in accordance with one embodiment of the present invention. Referring to FIG. 7, the primary receiver unit 104 (FIG. 1) in one aspect may be configured to retrieve or generate a close proximity command (710) for transmission to the transmitter unit 102. To establish the transmission range (720), the primary receiver unit 104 may be positioned physically close to (that is, within a predetermined distance from) the transmitter unit 102. For example, the transmission range for the close proximity communication may be established at approximately one foot distance or less between the transmitter unit 102 and the primary receiver unit 104. When the transmitter unit 102 and the primary receiver unit 104 are within the transmission range, the close proximity command, upon initiation from the receiver unit 104 may be transmitted to the transmitter unit 102 (730).

Referring back to FIG. 7, in response to the transmitted close proximity command, a response data packet or other responsive communication may be received (740). In one aspect, the response data packet or other responsive communication may include identification information of the transmitter unit 102 transmitting the response data packer or other response communication to the receiver unit 104. In one aspect, the receiver unit 104 may be configured to generate a key (for example, an 8 bit key or a key of a predetermined length) based on the transmitter identification information (750), and which may be used in subsequent close proximity communication between the transmitter unit 102 and the receiver unit 104.

In one aspect, the data communication including the generated key may allow the recipient of the data communication to recognize the sender of the data communication and confirm that the sender of the data communication is the intended data sending device, and thus, including data which is desired or anticipated by the recipient of the data communication. In this manner, in one embodiment, one or more close proximity commands may be configured to include the generated key as part of the transmitted data packet. Moreover, the generated key may be based on the transmitter ID or other suitable unique information so that the receiver unit 104 may use such information for purposes of generating the unique key for the bidirectional communication between the devices.

While the description above includes generating the key based on the transmitter unit 102 identification information, within the scope of the present disclosure, the key may be generated based on one or more other information associated with the transmitter unit 102, and/or the receiver unit combination. In a further embodiment, the key may be encrypted and stored in a memory unit or storage device in the transmitter unit 102 for transmission to the receiver unit 104.

FIG. 8 is a flowchart illustrating sensor insertion detection routine in the data monitoring and management system of FIG. 1 in accordance with one embodiment of the present invention. Referring to FIG. 8, connection to an analyte sensor is detected (810) based on, for example, a power up procedure where the sensor conduction trace 611 (FIG. 6) is configured to establish electrical contact with a predetermined one or more contact points on the transmitter unit 102. That is, when the sensor 101 (for example, the electrodes of the sensor) is correspondingly connected to the contact points on the transmitter unit 102, the transmitter unit 102 is configured to close the circuit connecting its power supply (for example, the battery 621 (FIG. 6)) to the components of the transmitter unit 102 and thereby exiting the power down or low power state into active or power up state.

In this manner, as discussed above, in one aspect, the transmitter unit 102 may be configured to include a power supply such as a battery 621 integrally provided within the sealed housing of the transmitter unit 102. When the transmitter unit 102 is connected or coupled to the respective electrodes of the analyte sensor that is positioned in a transcutaneous manner under the skin layer of the patient, the transmitter unit 102 is configured to wake up from its low power or sleep state (820), and power up the various components of the transmitter unit 102. In the active state, the transmitter unit 102 may be further configured to receive and process sensor signals received from the analyte sensor 101 (FIG. 1) (830), and thereafter, transmit the processed sensor signals (840) to, for example, the receiver unit 104 (FIG. 1).

Accordingly, in one aspect, the sensor 610 (FIG. 6) may be provided with a conduction trace 611 which may be used to wake up or exit the transmitter unit from its post manufacturing sleep mode into an active state, by for example, establishing a closed circuit with the power supply provided within the transmitter unit 102.

FIG. 9 is a flowchart illustrating sensor removal detection routine in the data monitoring and management system of FIG. 1 in accordance with one embodiment of the present invention. Referring to FIG. 9, when the sensor removal is detected (910) for example, based on detaching or removing the transmitter unit 102 that was in contact with the sensor 101, one or more status signal is generated (920), that includes, for example, an indication that the sensor removal state has been detected, and/or an indication that the transmitter unit 102 will enter a sleep mode or a powered down status. Thereafter, the generated status signal in one aspect is transmitted, for example, to the receiver unit 104 (930), and the transmitter unit 102 is configured to enter the power down mode or low power sleep mode (940).

In this manner, in one aspect, when the transmitter unit 102 is disconnected from an active sensor 101, the transmitter unit 102 is configured to notify the receiver unit 104 that the sensor 101 has been disconnected or otherwise, signals from the sensor 101 are no longer received by the transmitter unit 102. After transmitting the one or more signals to notify the receiver unit 104, the transmitter unit 102 in one embodiment is configured to enter sleep mode or low power state during which no data related to the monitored analyte level is transmitted to the receiver unit 104.

FIG. 10 is a flowchart illustrating the pairing or synchronization routine in the data monitoring and management system of FIG. 1 in accordance with one embodiment of the present invention. Referring to FIG. 10, in one embodiment, the transmitter unit 102 may be configured to receive a sensor initiate close proximity command (1010) from the receiver unit 104 positioned within the close transmission range. Based on the received sensor initiate command, the transmitter unit identification information may be retrieved (for example, from a nonvolatile memory) and transmitted (1020) to the receiver unit 104 or the sender of the sensor initiate command.

Referring back to FIG. 10, a communication key optionally encrypted is received in one embodiment (1030), and thereafter, sensor related data is transmitted with the communication key on a periodic basis such as, every 60 seconds, five minutes, or any suitable predetermined time intervals (1040).

Referring now to FIG. 11, a flowchart illustrating the pairing or synchronization routine in the data monitoring and management system of FIG. 1 in accordance with another embodiment of the present invention is shown. That is, in one aspect, FIG. 11 illustrates the pairing or synchronization routine from the receiver unit 104. Referring back to FIG. 11, the sensor initiate command is transmitted to the transmitter unit 102 (1110) when the receiver unit 104 is positioned within a close transmission range. Thereafter, in one aspect, the transmitter identification information is received (1120) for example, from the transmitter unit that received the sensor initiate command. Thereafter, a communication key (optionally encrypted) may be generated and transmitted (1130) to the transmitter unit.

In the manner described above, in one embodiment, a simplified pairing or synchronization between the transmitter unit 102 and the receiver unit 104 may be established using, for example, close proximity commands between the devices. As described above, in one aspect, upon pairing or synchronization, the transmitter unit 102 may be configured to periodically transmit analyte level information to the receiver unit 104 for further processing.

FIG. 12 is a flowchart illustrating the power supply determination in the data monitoring and management system of FIG. 1 in accordance with one embodiment of the present invention. That is, in one embodiment, using a counter, the receiver unit 104 may be configured to determine the power supply level of the transmitter unit 102 battery so as to determine a suitable time for replacement of the power supply or the transmitter unit 102 itself. Referring to FIG. 12, periodic data transmission is detected (1210), and a corresponding count in the counter is incremented for example, by one with each detected data transmission (1220). In particular, a Hobbs counter may be used in the rolling data configuration described above to provide a count that is associated with the transmitter unit data transmission occurrence.

Referring to FIG. 12, the updated or incremented count stored in the Hobbs counter is periodically transmitted in the data packet (1230) from the transmitter unit 102 to the receiver unit 104. Moreover, the incremented or updated count may be stored (1240) in a persistent nonvolatile memory unit of the transmitter unit 102. Accordingly, based on the number of data transmission occurrences, the battery power supply level may be estimated, and in turn, which may provide an indication as to when the battery (and thus the transmitter unit in the embodiment where the power supply is manufactured to be embedded within the transmitter unit housing) needs to be replaced.

Moreover, in one aspect, the incremented count in the Hobbs counter is stored in a persistent nonvolatile memory such that, the counter is not reset or otherwise restarted with each sensor replacement.

FIG. 13 is a flowchart illustrating close proximity command for RF communication control in the data monitoring and management system of FIG. 1 in accordance with one embodiment of the present invention. Referring to FIG. 13, a close proximity command associated with communication status, for example is received (1310). In one aspect, the command associated with the communication status may include, for example, a communication module turn on or turn off command for, for example, turning on or turning off the associated RF communication device of the transmitter unit 102. Referring to FIG. 13, the communication status is determined (1320), and thereafter, modified based on the received command (1330).

That is, in one aspect, using one or more close proximity commands, the receiver unit 104 may be configured to control the RF communication of the transmitter unit 102 to, for example, disable or turn off the RF communication functionality for a predetermined time period. This may be particularly useful when used in air travel or other locations such as hospital settings, where RF communication devices need to be disabled. In one aspect, the close proximity command may be used to either turn on or turn off the RF communication module of the transmitter unit 102, such that, when the receiver unit 104 is positioned in close proximity to the transmitter unit 102, and the RF command is transmitted, the transmitter unit 102 is configured, in one embodiment, to either turn off or turn on the RF communication capability of the transmitter unit 102.

FIG. 14 is a flowchart illustrating analyte sensor identification routine in accordance with one embodiment of the present invention. Referring to FIG. 14, periodically, sensor counter information is received (1410), for example included as rolling data discussed above. The received sensor counter information may be stored in one or more storage units such as a memory unit. When the sensor counter information is received, a stored sensor counter information is retrieved (1420), and the retrieved sensor counter information is compared with the received sensor counter information (1430). Based on the comparison between the retrieved sensor counter information and the received sensor counter information, one or more signal is generated and output (1440). That is, in one aspect, the sensor counter in the transmitter unit 102 may be configured to increment by one with each new sensor replacement. Thus, in one aspect, the sensor counter information may be associated with a particular sensor from which monitored analyte level information is generated and transmitted to the receiver unit 104. Accordingly, in one embodiment, based on the sensor counter information, the receiver unit 104 may be configured to ensure that the analyte related data is generated and received from the correct analyte sensor transmitted from the transmitter unit 102. A method in one embodiment includes detecting a data transmission, incrementing a count associated with the detected data transmission, and storing the count. The count may be incremented by one. In a further aspect, the method may include associating a power supply level information with the stored count.

Moreover, the method may also include generating a signal associated with the stored count, and/or include outputting the generated signal, where outputting the generated signal may include one or more of visually displaying the generated signal, audibly outputting the generated signal, or vibratory outputting the generated signal.

In yet another aspect, the method may include transmitting the count with the data transmission, where the count may be transmitted periodically with the data transmission.

In still another aspect, the method may include associating a power supply status with the count.

A data processing device in another embodiment may include a counter, a data communication unit, and a data processing section coupled to the data communication unit and the counter, the data processing section configured to increment a count stored in the counter based on data transmission by the data communication unit.

In one aspect, the counter may include a nonvolatile memory unit. The counter may include an EEPROM. The data communication unit may include an RF transceiver. The count stored in the counter may be incremented by one with each data transmission by the data communication unit.

The device may include a power supply coupled to the data processing unit, the data communication unit and the counter, where the count stored in the counter is not erased when the power supply is disabled or in low power state.

The data processing unit may be configured to estimate the power supply life based on the stored count in the counter. The device in a further aspect may include an output section for outputting one or more signals associated with the count information, where the output section may include one or more of a display unit, an audible output section, or a vibratory output section.

In accordance with another aspect of the invention, elapsed sensor life and/or remaining sensor life is determinable. In this regard the sensor life is tracked by a counter. Advantageously, after a system failure such as power shut-down, power loss, reset (e.g., Watchdog reset), battery drain, battery failure, the user of the data monitoring and management system of FIG. 1 no longer needs to replace the sensor. Instead, the methods and system of the invention provide sensor life information to the user to enable the user to restart the analyte monitoring system using the same sensor, provided suitable remaining sensor life.

In one embodiment of the invention, as shown in FIG. 1, an analyte monitoring and management system includes an analyte sensor 101, a transmitter unit 102, a first counter (not shown), such as a Hobbs counter, and a receiver unit 104. The system can be configured to determine the elapsed life (or remaining life) of an employed analyte sensor 101. Advantageously, a user of the analyte monitoring system is now able to determine a suitable time for replacement of the analyte sensor, for example, in the event of a system failure during which the receiver loses data information about calibration schedule and/or sensor expiration schedule. Prior systems typically require the user to discard the analyte sensor (regardless of remaining life available on the sensor) after the occurrence of a system failure due to the data loss of time and day and calibration.

In accordance with one embodiment of the method, a signal associated with initiation of an analyte sensor is provided. For example, but not limitation, upon initiation of the sensor 101 a signal is generated which contains analyte measurement information. The signal can be at least part of the data which forms a data packet that is encoded by the transmitter unit 102 and/or transmitted via a communication link to a receiver unit 104. The receiver unit 104 can be configured to expect receipt of a data packet at predetermined time intervals and/or at periodic calculations of analyte. In one embodiment, the data packets are transmitted by a transmitter unit 102 to receiver unit 104 every minute. After the count temporally associated with initiation of the sensor is stored, the counter is configured to continually count by increments. The increments can be for example, based on a periodic cycle, such as a measurement cycle. Alternatively, the increment can be based on other factors, such as scheduled time interval. Additionally, the incremental count can be commensurate with the transmission of each (or a predetermined limited number) data packets and/or measurement cycles. Thus, for example, the measurement cycle can be a periodic calculation of measured analyte (regardless of whether it is transmitted), or it can be based on a selected time interval, such as for example 30 or 60 seconds, if desired. In some embodiments, the count information incrementally counted by the counter is transmitted to the receiver unit 104 as part of the data packet. Further, the receiver is configured to extract the count from the data packet.

In one embodiment, the count information transmitted in the data packet upon sensor initiation is transmitted to receiver unit 104 where it is stored. Preferably, the count information is stored in nonvolatile memory such that it is not lost during a system failure. Preferably, the nonvolatile memory device is disposed in the receiver unit 104. However, transmitter unit 102 can be configured to store the count. The counter which can be part of the transmitter device 102, for example, is a Hobbs counter.

In accordance with one embodiment of the invention, elapsed life of an analyte sensor (or remaining life expectancy of a sensor) can be determined by comparing the stored count which is based on sensor initiation with an incremented count. As described above, the incremental count is based on a known measurement cycle, and/or time interval. Thus, the comparison of the count information can be used to calculate the duration or elapsed time of the sensor use.

Further, the determined elapsed time can be used to restart operating system timers, such as a sensor life timer and/or calibration timer.

FIG. 15 is a flowchart illustrating a method for determining elapsed life of an analyte sensor employed in the analyte monitoring and management system of FIG. 1. As depicted and embodied herein, an analyte sensor is initiated (1510) to detect and/or measure the presence of an analyte in a bodily fluid. For the purpose of illustration, but not limitation, the analyte can be glucose and the bodily fluid can be blood, plasma or interstitial fluid. However, other analytes can be monitored, such as but not limited to lactate. A counter, such as for example a Hobbs counter described above, is configured to incrementally count. The Hobbs counter may be disposed for example in the transmitter of the analyte monitoring system. The count or value that is temporally associated with the initiation of the sensor (1520) (or a signal generated by the sensor during initiation) is stored in a memory unit (count 1) (1530). In addition to the storage of the first count, the counter continues to incrementally count. As described, the incremental count can be based on a known measurement cycle, such as that of the analyte sensor detecting levels of an analyte in the bodily fluid. Alternatively, the incremental count can be based on a time interval. In the event that a system failure occurs, the counter is configured to store a second count temporally associated with re-initiation of the analyte sensor (count 2) (1540). In this regard, the elapsed time or duration of use of the analyte sensor prior to the fault condition can be determined by comparing count 2 and count 1 (1550). Thus, provided that at least some life expectancy of the analyte sensor remains, the user may continue to use the analyte sensor, rather than being required to change the sensor with a replacement sensor because all data was lost. In the event that no or less than a predetermined amount of life remains on the analyte sensor, the monitoring system can be configured to display a message or alarm that the sensor expired or is soon to expire (1560). In a further embodiment, the determined elapsed time can be used to restart a sensor life timer and/or calibration timer (1570).

The term system failure as used herein means a fault condition such as any condition by which the analyte monitoring system loses power. Some non-limiting examples of fault conditions include a reset (e.g., receiver reset), battery drain, battery replacement, power loss, power shut-down, or a fatal error. Typically, after such fault conditions, analyte monitoring systems prompt the user to replace the sensor because information about the life of the sensor was lost at the time of the fault condition. This aspect of the invention, allows the use of the same sensor after a fault condition occurs (provided that the sensor life has not expired), thereby saving the user costs associated with using a new sensor and the hardship of undergoing another calibration schedule.

In another embodiment of the invention, the analyte monitoring and management system includes a first counter to incrementally count based on a time interval, or calculation of an analyte, and a second counter to incrementally count by one only if a new sensor is initiated. In this regard, the incremental count of the second sensor can indicate how many or which sensor is being employed. For example, if the second counter has an incremental count of one, then the first sensor is being employed, if the second counter has an incremental count of 2, then the second sensor is being employed. Thus, the second counter can track how many sensors have been employed. In a further aspect of the invention, if the receiver connects to the transmitter and in response the receiver receives a count change compared to the sensor count before the system failure, the receiver acknowledges that a different sensor was implanted or otherwise employed during the receiver shut down. In this regard, the previous sensor life time is terminated, and a new count begins for the new sensor. Additionally, when the second counter increments by one because a new sensor is used then the count of the first counter is stored.

Referring to another embodiment of the invention, as described in FIG. 16, the first counter can be a Hobbs counter which is initiated (for example, to T=0) (1610). Thereafter the Hobbs counter incrementally counts (for example, to T=T+1) (1620). The second counter can be for example a sensor counter that is configured to count incrementally with the initiation of each new analyte sensor (for example, S=S+1) (1640). Thus, if there is no new sensor employed, the count of the second counter does not increment (1630). Further, a count of the Hobbs counter (1650) (which is commensurate with an incremental count of the sensor counter) is stored (1660). Thus, the system contains stored data regarding the data and time of each new sensor initiation. Accordingly, the first and second counters in conjunction can be used to determine elapsed life of the analyte sensor. As shown in FIG. 16, if the sensor life is less than the sensor life expectancy (1670), then the cycle is repeated. If the sensor life is expired or close to its expiration, then an alarm or message can be output (1680).

In one embodiment, the first counter is a 20-bit counter, and the second counter is an 8-bit counter. However, other types of counters can be utilized.

In another aspect of the invention, an output unit is provided. The output unit can be configured to display a value derived from the count information. In this regard, the output unit can be a display device. The display device can be an Organic Light Emitting Diode (OLED) display device, for example, a small molecule or polymer OLED. The OLED display device can provide wide viewing angles, high brightness, colors, and contrast levels.

It will be apparent to those skilled in the art that various modifications and alterations in the methods and systems of this invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Although the invention has been described in connection with specific embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. It is intended that the following claims define the scope of the present invention and that structures and methods within the scope of these claims and their equivalents be covered thereby. 

What is claimed is:
 1. A system, comprising: an analyte sensor to measure an analyte level; a receiving device; and sensor electronics communicatively coupled to the analyte sensor and the receiving device, the sensor electronics configured to: store a first count; periodically increment the first count; detect a fault condition associated with a system failure; and when the fault condition is detected, store a second count associated with a time of re-initiation of the analyte sensor.
 2. The system of claim 1, wherein the fault condition comprises a condition in which one of the analyte sensor, receiving device or sensor electronics loses power.
 3. The system of claim 2, wherein the condition in which one of the analyte sensor, receiving device or sensor electronics loses power comprises a reset, battery replacement, power loss, power shut-down, or fatal error.
 4. The system of claim 1, wherein the receiving device is configured to receive the first count and the second count from the sensor electronics, and to compare the first count and the second count to determine a duration of use of the analyte sensor prior to the fault condition, and to determine a remaining sensor life expectancy based on the duration of use of the analyte sensor prior to the fault condition.
 5. The system of claim 4, wherein the receiving device is further configured determine that the remaining sensor life expectancy is less than a predetermined amount, and in response to notify a user that the analyte sensor is soon to expire.
 6. The system of claim 4, wherein the receiving device is further configured to restart a sensor life timer based on the duration of use.
 7. The system of claim 1, wherein the first count is periodically incremented according to a measurement cycle.
 8. The system of claim 1, wherein the analyte sensor comprises a plurality of electrodes including a working electrode comprising an analyte-responsive enzyme bonded to a polymer disposed on the working electrode.
 9. The system of claim 8, wherein the analyte-responsive enzyme is chemically bonded to the polymer.
 10. The system of claim 8, wherein the working electrode further comprises a mediator.
 11. The system of claim 1, wherein the analyte sensor comprises a plurality of electrodes including a working electrode comprising a mediator bonded to a polymer disposed on the working electrode.
 12. The system of claim 11, wherein the mediator is chemically bonded to the polymer.
 13. A method, comprising: providing an analyte sensor to measure an analyte level; providing sensor electronics communicatively coupled to the analyte sensor and a receiving device; storing a first count; periodically incrementing the first count; detecting a fault condition associated with a system failure; and when the fault condition is detected, storing a second count associated with a time of re-initiation of the analyte sensor.
 14. The method of claim 13, wherein the fault condition comprises a condition in which one of the analyte sensor, receiving device or sensor electronics loses power.
 15. The method of claim 14, wherein the condition in which one of the analyte sensor, receiving device or sensor electronics loses power comprises a reset, battery replacement, power loss, power shut-down, or fatal error.
 16. The method of claim 13, wherein the analyte sensor comprises a plurality of electrodes including a working electrode comprising an analyte-responsive enzyme bonded to a polymer disposed on the working electrode.
 17. The method of claim 16, wherein the analyte-responsive enzyme is chemically bonded to the polymer.
 18. The method of claim 16, wherein the working electrode further comprises a mediator.
 19. The method of claim 13, wherein the analyte sensor comprises a plurality of electrodes including a working electrode comprising a mediator bonded to a polymer disposed on the working electrode.
 20. The method of claim 19, wherein the mediator is chemically bonded to the polymer. 